The pair were arrested after a neighbour managed to take a picture of the now 19-year-old being forced to pull a cart while being whipped.
Betina Siger lived in the village of Karavlasi in the northeast part of Bosnia with her stepparents. Her stepfather had once been married to her mother.
On May 15, Betina was spotted by neighbour Saed Makalic. When he saw the teen she was pulling a cart occupied by her stepfather and one of his friends. She was pulling the cart in the way a horse would pull it and her father was whipping her.
Makalic pulled out his cellphone, took a picture of the inhumane treatment Betina was receiving, and showed the photo to local police. Two days later Milenko Marinkovic, 52, and his wife Slavojka, 45, were arrested on suspicion of illegal imprisonment and cruel treatment.
As reported by ABC News, Makalic had first met Marinkovic when he helped him build his house. He said, I did not pay too much attention to the girl, but I saw her several years ago when she was eating pig food from a dog bowl.
At that time authorities went to the home, but Marinkovic and his wife were successful in hiding Betina.
It is believed Marinkovic married Betina's mother, a German citizen, to be able to obtain residency in Germany. The mother came to Bosnia with her five daughters and the other four married Marinkovic's brothers. They are now living abroad in Germany and Austria.
Betina's mother still lives near the Marinkovics and is currently being investigated by police.
Admir Arnautovic, a spokesman for the prosecutor's office in Tuzla, was quoted in the Daily Mail as saying, The girl was not allowed to communicate with people, did not go to school, was starved, beaten and forced to do hard labour.
Saying she had visible signs of torture all over her body, Arnautovic added, "I've been in this business a long time, and this is the first time I've ever seen anything of this nature."
Betina, who was taken to a safe house, weighs 88 pounds and is not doing well.
Other than Makalic, who has become a hero in Bosnia, it is not known whether other neighbours in the village knew about the horrific treatment the teen had been subjected to.